Migrating servers to new host and SAN

[qibt_dean]

Hi,

Current setup:

2x ESXi servers, local storage, shared nothing.  VMWare Essentials licence

New setup:

3 x ESXi servers, Eqllogic SAN. VMWare Essential Plus licence

I would like to transition to the new setup with minimal downtime, we have some large (>1TB) guests on one of the servers and I dont want these to be offline for more than a few minutes, so a cold migration is out of the question.

I had a thought that I could put the Essential Plus licence on the old servers and 1 of the new servers, attach the new SAN to the old servers, then use VMWare replication to replicate VMs from one of the old servers to the new server/storage, then do a recovery.

I would then remove that old server from Vsphere, add a new server and move the licence, then perform the same task on the 2nd old server.

Once that is complete I would remove the 2nd old server, add the 3rd new server and move the licence.

Can anyone tell me if this is a feasible option, or suggest alternatives?

Thanks

Dean.

[bayupw · Accepted solution]

Hi Dean,

VMware Replication (vSphere Replication) will requires downtime when you perform Recovery from old host to new host.

How long can you afford for downtime?

The Recovery process will turn off the the source/protected VM at the current host (depends on VM how long it would normally take to perform a guest shutdown) and the destination/recovery VM will be powered on at the new host (again, depends on VM how long it would normally take for OS and services to up during a normal power on process).

vSphere Replication requires vSphere Web Client, and other requirements as described here: vSphere 5.5 Documentation Center - vSphere Replication System Requirements

Do you have a vCenter server?
Which version of ESXi (and vCenter) are you using?

If you do not have a vCenter Server yet, I would suggest you to install a vCenter server and add all the current 2 ESXi hosts + 1 new ESXi host.

From there you will have a 3 ESXi host, then you can perform a migration from current to new ESXi host.

If you are using vSphere 5.1+ you can do vMotion even if the host do not have access to same storage see this: vSphere 5.5 Documentation Center  - Migration with vMotion in Environments Without Shared Storage

Its quite straight forward, if you are using vSphere 5.1+

- Make sure you have vCenter Server 5.1+ with vSphere Web Client

- Add current hosts + 1 new hosts

- Make sure the vMotion without Shared Storage requirements are met vSphere 5.5 Documentation Center - Requirements and Limitations for vMotion Without Shared Storage

- Perform vMotion without Shared Storage procedure from current host to new host + local storage to EqualLogic SAN - you can start with small VM and less critical VM first if you are not sure.

- Once all the VMs have been migrated to new hosts + EqualLogic SAN, you can safely do a maintenance mode on the current hosts and remove it from the vCenter server (vSphere licenses will be reclaimed)

- Add the remaining 2 new hosts.

If you are using vSphere prior 5.1, you would need to present the EqualLogic SAN to both new 1 new host and current 2 hosts.

After current hosts can see the EqualLogic SAN, perform a Storage vMotion (live migration the disks) from local storage to the EqualLogic.

For migration prior vSphere 5.1, there are 2 ways that I can think:

1. with vMotion - no downtime

There are some configuration requirements for vMotion to work: vSphere 5.5 Documentation Center - Migration with vMotion

Make sure your current and new hosts are running in the same CPU / EVC mode or matrix, you can check it here: http://www.vmware.com/resources/compatibility/search.php?deviceCategory=cpu

If they are on different EVC Mode, you can turn on the EVC on new hosts.

Steps are:

- Make sure the VMs are in EqualLogic (you can use Storage vMotion)

- Perform a vMotion from current hosts to new host.

- Once all the VMs have been migrated, you can safely do a maintenance mode on the current hosts and remove it from the vCenter server

- Add the remaining 2 new hosts to the vCenter.

2. without vMotion - requires downtime for cutover

This will be cold migration but without storage migration, it will require less downtime compare to directly cold migration from localdisk to shared storage.

Steps are:

- Make sure the VMs are in EqualLogic (you can use Storage vMotion)

- Power off the VMs from current hosts and migrate (cold) from old host to new host (you can also drag the VM and drop it to the new host).

- Once all the VMs have been migrated, you can safely do a maintenance mode on the current hosts and remove it from the vCenter server

- Add the remaining 2 new hosts to the vCenter.

[qibt_dean]

Fantastic answer, thanks Bayu, I am using vSphere5.5 on the old server and have a vCenter server, so the first option will work.

Appreciate your quick reply!